Steamfitter Certificate of Qualification (CFQ) Practice Exam

The use of a wooden or aluminum plug is commonly associated with the threading of plastic pipe because it provides stability and support during the threading process. When threading plastic pipe, using a plug can help to prevent the pipe from collapsing or deforming due to the pressure applied while threading. This ensures a clean and accurate thread, which is critical for creating secure joints in plastic piping systems. Proper threading is essential for maintaining the integrity and performance of the piping system.

The other choices do not serve the specific function of supporting or stabilizing the plastic pipe during threading. A metal clamp may secure the pipe, but it does not prevent deformation. A rubber sleeve could provide grip or protection but does not assist directly in the threading action. Teflon tape is used for sealing joints but is not involved in the actual threading process.